Notre Dame’s pass rush in the first five games can be summarized with Ishaq Williams’s one-on-one match up with Temple quarterback Connor Reilly in Week 1. Williams had Reilly cornered in an open backfield, but instead of wrapping Reilly up for a huge loss, Williams ran right past the quarterback and Reilly ended up with a decent gain out of the play.

Up until their six-sack performance against Arizona State (and the re-emergence of linebacker Prince Shembo), the Irish constantly found themselves chasing down a quarterback for what looked like a guaranteed sack only to have the quarterback either slip past the pursuing defenders or complete an improbable pass for a first down. In five games, the Irish registered three sacks.

Returning two All-American linemen was supposed to mean big things for the Irish pass rush, but personnel losses have depleted a chunk of Notre Dame’s depth in the front seven:

 Eddie Vanderdoes transferred,

 Danny Spond retired because of complications from chronic migraines,

 Sheldon Day was sidelined for the better part of three games by an ankle injury that has kept Sheldon Day.

Jarrett Grace’s season-ending knee injury against Arizona State has dealt the Irish defense another huge blow.

Notre Dame has only five interceptions on 235 passing attempts, two of which came against the Sun Devils, though part of the can be blamed of the non-existent pass rush for most of the year. It’s not so much that offenses are picking apart the secondary with big-chunk plays (opponents average 10.7 yards per pass), but that the Irish are struggling to tackle receivers who catch passes under coverage.

Temple, Michigan State, Purdue and Oklahoma exploited the defense’s tackling deficiencies by turning short passes and pitches into 8-, 9- and 10-yard gains.

Perhaps most telling of the drop-off between this year’s squad and last year’s squad: Notre Dame has allowed 13 touchdowns in six games. It allowed 11 all of last year.

Notre Dame may have righted the ship after its relatively smothering performance against Arizona State. With USC and Stanford’s skilled offenses and Navy and Air Force’s triple-option looming, the Irish will be put to the test in the second half of the season.

RUN DEFENSE: B-

Despite losing Kapron Lewis-Moore, Manti Te’o and the aforementioned injuries that have plagued the front seven, Notre Dame’s rush defense has rallied from a few early lapses to post 2012-esque performances against Purdue (38 yards), Michigan State (119 yards) and Arizona State (65 yards).

While the Irish aren’t the “Stanford goal line defense” of last year, they’re holding their opponents to 122 rushing yards a game (29th nationally) and 3.8 yards per carry. Both of Notre Dame’s worst run defense games came against the most mobile quarterbacks the team has faced, Michigan’s Devan Gardner and Oklahoma’s Blake Bell.

In fact, quarterbacks have combined for 223 of opponents’ 734 total rushing yards against the Irish. Gardner posted the biggest ground performance against Notre Dame to date with 82 rushing yards. Oklahoma’s Brennan Clay (78) and Michigan’s Fitzgerald Toussaint (72) are the only two running backs that have broken 70 yards on the Irish this season.

Part of that can be attributed to the fact that Notre Dame still has a pretty solid run defense. Part of that can also be attributed to the fact that opponents have realized they can succeed with short passes against the Irish and don’t have to rely on the run as much.

Freshman linebacker Jaylon Smith was targeted on the edge early in the season and made a few rookie mistakes, but he showed progress with a nine-tackle, swarm-to-everything day against Arizona State.

If Day can get healthy and back in the lineup and if Dan Fox and Carlo Calabrese can hold the ranks without Grace, the Irish run defense will only look up from here.